Latency of radiation-induced disease lasts much longer than 3 decades

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

The latency of radiation-induced differentiated thyroid cancer appears to last longer than 30 years.

Note that that most patients with thyroid cancer related to radiation in Chernobyl were diagnosed in advanced stages -- about 29% of patients had nodal involvement upon diagnosis and about 30% of patients had extra-thyroid tumor invasion.

"Children irradiated in 1986 still have a high risk of malignancy and need continued observation," said Sergiy Cherenko, MD, of the Ukrainian Scientific and Practical Center of Endocrine Surgery in Kyiv.

In his poster presentation at the International Thyroid Congress, Cherenko said that the medical community anxiously awaited the 10 to 15-year post-Chernobyl presumed peak of thyroid cancer, especially among the children born from 1982-1986.

But when he and his colleagues looked at cases after that time frame, they observed no waning in the percentage of people, who were young children at the time of Chernobyl, developing differentiated thyroid cancer, which is a manifestation of radiation-induced cancer.

"We calculated separately annual share and clinical peculiarities of thyroid cancer in patients who were 17 years of age at the moment of the Chernobyl catastrophe (born between 1969 and 1986) and the 1982-1986 born children among all thyroid carcinomas operated on in a single national endocrine surgery hospital since 2000," Cherenko stated.

"Surprisingly, the share of surgically operated thyroid cancer patients who were at a young age at the moment of the disaster did not shrink after 30 years," Cherenko told MedPage Today. The under 17 group composed 24.9% of all operated thyroid carcinomas in the 2000-2014 period; the youngest children represent 6.2% of that group.

In the years 2000-2004, the contribution of operated thyroid cancer among individuals born between 1968 and 1986 was 16.2% and the contribution of those born between 1982 and 1986 was 3.3%. Five years later (2005-2009), the entire group had an incidence of 21.4%. In 2010-2014, the total group incidence was 29.8% and the children from that period represented 7.9% of the the operated thyroid cancer.

Cherenko said that only one child among those included in his statistics was younger than 5 -- in other words that child missed the Chernobyl fallout.

"I am not surprised that the latency of radiation-induced thyroid cancer continues, even 30 years after the disaster at Chernobyl," Mario Silva, MD, professor of endocrinology at the University of Milan told MedPage Today. "If radiation is taken up by the thyroid, the risk of cancer will continue."

Cherenko said the radiation influence on thyroid cancer due to Chernobyl has been well-established, especially for children and adolescents who lived in the Ukraine at the moment of the disaster. The "Chernobyl children" carcinomas were defined as having short latency, multifocality, papillary type, and with spread to the lymph nodes. He noted that many patients were diagnosed in advanced stages -- about 29% of patients had nodal involvement upon diagnosis and about 30% of patients had extra-thyroid tumor invasion.

Cherenko questioned whether politics trumped health during the days after the explosion at Chernobyl, especially in the Ukraine and neighboring countries. He pointed out that school children marched down the streets of Kyiv on May Day, just days after the explosions, and were fully exposed to the atmosphere-laden radiation.

But in neighboring Poland, the government took steps to give prophylactic stable iodine tablets to more than 10 million children and another 8 million adults. Cherenko said none of the Polish children have been diagnosed with thyroid cancer that can be tied to Chernobyl.

Silva said that the success of the health administrators in Poland to get prophylaxis iodine to the general population was heroic and that health officials had to wrest the control of the stable iodine pills from the arms of the military which had stockpiled it in case of nuclear attack.

Cherenko and co-authors disclosed no relevant relationships with industry.

Silva disclosed no relevant relationships with industry.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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